This invention relates to the field of catalyst systems and catalyst processes.
Ethylene polymerized by chromium/silica catalyst technology is known in the art. The polyethylene resins produced by this technology will generally have a high molecular weight. Hydrogen, which is a known molecular weight reducer in titanium trichloride catalyst systems, will generally have little effect on the molecular weight of polyethylene resins produced by chromium/silica catalyst systems. This invention provides a chromium/silica catalyst system that has a high sensitivity to hydrogen. These chromium/silica catalyst systems will produce lower molecular weight polyethylene resins when hydrogen is used to modify the molecular weight of these polyethylene resins.